This invention relates generally to data transfer between a source device and a target device and, more particularly, to an image data transfer mechanism between a source device incapable of generating image data that is paced and a target device that receives the image data via memory that is allocated as a frame buffer.
Prior art solutions have existed for transferring digital images from a source device to a target device. For example, prior art scanners are oftentimes coupled with a printer so as to form a copy machine. Once the scanner begins scanning data from a document, processing circuitry should be able to receive the entire page of image data at the speed with which it is scanned via the scanner. Accordingly, a significant amount of memory is required for such implementations. Additionally, a typical scanner does not contain a buffer, and furthermore the scanner cannot be paced in order to slow down the amount of image data that is transferred to the printer. For example, the amount of image data from one page of a document can be up to 45 megabytes, for an 11-inch by 17-inch page that is scanned at 8 bits per pixel, 400 dots per inch by 600 dots per inch. Hence, the memory requirements are significant.
In order to deliver copy devices to small business and home user environments, there is a need to minimize the amount of memory required by a target device, such as a printer, such that the product can remain cost-competitive. In fact, substantial efforts have recently been directed to reducing the amount of required memory in laser printers specifically to enhance performance while at the same time improving cost-effectiveness and size.
Prior art techniques that attempt to reduce the amount of memory required between a source device and a target device all involve compromises which affect performance. For the case where a printer and a copier are coupled together via a copy processor card and an IEEE 1394 interface, a card slot is provided for receiving a copy processor card which forms a serial bus interconnecting the scanner and printer. Such scanner and printer form a copier. In order to maintain competitive costs, no buffer is provided on the scanner. Accordingly, the source device, or scanner, must be paced in order to limit the amount of image data delivered at speed to the printer. For this example, one of several solutions need to be implemented to overcome data transfer problems.
According to one solution, the scanner is provided with a start-stop mechanism. A controller on the scanner is provided for scanning part of a document page, with the controller stopping until a receiver is ready to receive more data, then continuing when the receiver is ready. However, many scanners are not provided with this capability. For those scanners that are provided with such capability, there exist scan quality issues, such as banding, which result from the start-stop capability.
According to another solution, a scanner is provided with a frame buffer. The provision of a frame buffer results in particular disadvantages in that this form of memory is dedicated to a single purpose and cannot be used for any other purpose. Accordingly, additional memory is required for imparting additional functionality, which increases cost and complexity.
Yet another solution comprises providing a frame buffer for a copy processor card. However, this implementation has the same disadvantage discussed above, in that the memory is dedicated for a single purpose. Therefore, additional memory is required for addressing additional purposes. There exists a further additional disadvantage in that a trade-off must be made due to space constraints in the card between the amount of memory that can be placed on the copy processor card, and the number of imaging copy processors, or digital signal processing chips, that can be provided on the card in order to pace data at the source device. More particularly, it is a disadvantage in that such implementation requires a source copy processor card. Alternatively, this implementation requires the provision of such copy processors being placed directly on the scanner mechanism itself.
Yet another solution includes providing a frame buffer on the input/output (I/O) card of the printer. Such implementation has the same above-mentioned disadvantage in that the memory is dedicated to a single purpose.
This invention relates to improvements for transferring image data from a source device to a target device to more efficiently, compactly, and cost effectively transfer such images, particularly as it relates to use with multiple function machines.
This invention solves the problem of receiving image data when flow control cannot be performed between a source device such as a scanner and a target device such as a printer.
According to one aspect of the invention, an image data transfer mechanism is disclosed having a source device, processing circuitry, and a target device. The source device is operative to transmit digital data. The processing circuitry is coupled to the source device for receiving the image data from the source device. The target device has memory, and is coupled with the processing circuitry. The target device is operative to receive the image data, while the memory is allocatable as a frame buffer for receiving the image data.
According to another aspect of the invention, an image data transfer mechanism is disclosed which includes a scanner, circuitry, an input/output controller, and a printer. The scanner is operative to capture image data. The circuitry is configured to deliver the image data at a rate corresponding substantially with the rate with which the image data is captured. The input/output controller is coupled with the circuitry and is configured to receive and process the image data substantially at the rate with which the image data is delivered. The printer has allocatable memory operative to receive the delivered image data.
According to yet another aspect of the invention, a method is disclosed for transferring image data from a source device to a target device wherein the source device cannot be paced, comprising: generating a digital image in the form of image data with a source device; providing a target device having allocatable memory; allocating a frame buffer in the memory for receiving the image data; and transferring the image data from the source device to the frame buffer of the target device.
Objects, features and advantages are to provide an apparatus and method for transferring image data between a source device and a target device in a manner that is relatively accurate, efficient, cost-effective and competitive, economical and smaller in size and weight.